If it were me I would definitely remove it from the display tank. I would be tempted to keep it in a species tank though. When they get a bit larger some of them have some interesting colors.
I used to net those things, but I finally managed to get rid of those pesky critters in my 40G. It took awhile, but once I located the colony, I boiled that #@#*&! Actually, I ran hot tap water over it and brushed it off with a stiff toothbrush.
